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12 terms

Adiabatic Processes

Lecture #11
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adiabatic
term for processes in which no heat energy is added or removed, but in which the temperature changes
warm/less dense air (lighter)
rises
cold/denser air (heavier)
sinks
as a parcel of air rises
-it expands (volume changes)
-it comes under less and less pressure as it rises in the atmosphere and thus expands
-as the air expands, the molecular action (kinectic energy) decreases and thus the temperature decreases
expanding air
= temperature decreases
compressing air
= temperature increases
Adiabatic Temperature Change
changing the temperature of the air without adding or subtracting heat (simply the result of compressing the air or allowing it to expand)
P (mb) = T ( ° K) x p (kg/m3) x C (2.87)
at the surface as temperature decreases, density and pressure increases; as the temperature increases, air density and pressure decreases
rate of adiabatic change
the rate at which the air temperature changes as it rises or falls through the atmosphere
dry adiabatic rate (DAR or DALR)
-when air is unsaturated (air temperature > dew point temperature; RH < 100% )
-the DAR is a constant rater of 1°C/100m or 10°C/1000m
-rising air cools at 1°C/100m (10°C/1000m)
-falling air warms at 1°C/100m (10°C/1000m)
wet or saturated adiabatic rate (SAR or SALR)
-when the air is saturated; air temperature = dew point temperature; RH = 100%
-the SAR is not a constant rate but a variable rate: 5°-9°C/100m
condensation level
height at which condensation occurs; where cloud formation begins (usually at the bottom of a cloud mass)